Retro-Mutagen aka Retro Mutagen or RetroMutagen, is a weapon of the Ninja Turtles. This is an orange substance that was created by Donatello, which serves as a cure for the effects of the Mutagen. Retro-Mutagen debuts in The Lonely Mutation of Baxter Stockman.
After the mutation of Kirby O'Neil into Kirby Bat occurred, Donatello became determined to create Retro-Mutagen to cure his mutation and also to cure other mutants. After months of attempting to create Retro-Mutagen out of the Mutagen, Donatello had failed until the time came that the Ninja Turtles discovered that April O'Neil was half human and half Kraang. After this discovery, Donnie figured that April might have an immunity to the Mutagen, which made him use some of April's DNA to create the cure. Until many days of working in his laboratory, Donatello had finally created Retro-Mutagen.
How it Retro-Mutates
When the Retro Mutagen comes in contact with a mutant organism, it can reverse the effects of the Mutagen. With the effects of the Mutagen being reversed, the mutant will be transformed back into its previous form. It can retro-mutate any mutant if it consumed, injected, or skin contact.
Characters that were Retro-Mutated
- Kirby Bat: He was once a mutant bat, but was retro-mutated into a human named Kirby O'Neil.
- Human Kraang Hybrids: They were all mutant human/ Kraang hybrids, but they were retro-mutated into humans.
- Creepweed: He was once a super mutant human/earth/plant hybrid, but was retro-mutated into a pile of plant goop.
- Baxter Fly: He was once a mutant human/ housefly hybrid, but was retro-mutated into a human named Baxter Stockman.
- In The Lonely Mutation of Baxter Stockman, Donatello finally succeed into creating the Retro-Mutagen.
- One key ingredient of the Retro-Mutagen that is known is DNA from April O'Neil, which makes the formula function due to her being half human and human Kraang.
- In Vengeance is Mine, there was an orange substance inside of Baxter Stockman's Laboratory that is speculated to be the Retro-Mutagen, which fell into the Mindless Serpent Serum after Baxter Fly spilled some into the mix.
- Possibly due to the Retro-Mutagen that was mixed into the Mindless Serpent Serum, Serpent Karai gained the ability to shape-shift.
- In Serpent Hunt, it was revealed that Serpent Karai has an immunity to Retro-Mutagen]].
- In Battle for New York Part One, Michelangelo accidentally developed a plutonium that enhanced the Retro-Mutagen into converting normal Mutagen into Retro-Mutagen.
- In Owari, as part of his dark attire, Donatello carried around two Retro-Mutagen Light Bulbs that were intended to be used on Super Shredder.